Generally, heavy oil, including diesel oil, natural gasoline, straight-run gasoline and cracked gasoline produced in the petroleum industry, contains various sulfur compounds.
These sulfur compounds cause serious pollution of heavy oil, and heavy oil containing these sulfur compounds is discharges noxious and corrosive sulfur oxides when it burns.
Desulfurization is a process of producing low-sulfur petrochemicals by removing the sulfur compounds having the above problems from heavy oil. In the desulfurization process, the sulfur compounds are removed from heavy oil using a high-pressure reactor.
That is, in the desulfurization process, the high-pressure reactor is filled with a catalyst for accelerating a desulfurization reaction, and then the sulfur compounds contained in heavy oil are removed using the catalyst, thereby producing low-sulfur petrochemicals.
Meanwhile, in this desulfurization process, since an exothermic reaction is conducted in the high-pressure reactor, reaction temperature becomes high. This high reaction temperature influences desulfurization conditions, catalyst, and the like, and thus it is very important to accurately measure this reaction temperature.
In order to accurately measure the reaction temperature, the high-pressure reactor used in the desulfurization process is provided with a thermowell.
This thermowell is welded at the front end of a protection tube passing through the body of the high-pressure reactor, so as to be immersed in the catalyst charged in the high-pressure reactor. A temperature sensor is inserted into the thermowell and protection tube to measure the actual temperature of the catalyst.
Accordingly, the temperature of the catalyst measured by the temperature sensor can be monitored in real time in a process control room through a temperature transmission unit.
However, such a conventional thermowell is problematic in that it is easily influenced by slight movement of the catalyst in the desulfurization process, and thus a portion in which the protection tube is welded thereto becomes easily damaged, and in that, when noxious gases leak out through the damaged portion thereof, the desulfurization process must be instantly stopped.
The high-pressure reactor is operated at a high pressure of about 160 kg/cm2 and a high temperature of about 440° C., and includes hydrogen sulfide (H2S) and ammonia (NH3) in concentrations of 1,000 ppm therein. When the noxious high-temperature and high-pressure gases leak out through the damaged portion of the thermowell, there is problematic in that human life and the environment are seriously damaged.